与三角形相关的问题

//已知三点坐标求三角形面积 
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
#define MAX 100
int main()
{
    int x1,y1,x2,y2,x3,y3,i=0;
    double a,b,c,s,p,ss[MAX];
    cin>>x1>>y1>>x2>>y2>>x3>>y3;
    while(x1 || y1 || x2 || y2 || x3 || y3)
    {
        a=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
        b=sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
        c=sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
        p=(a+b+c)*0.5;
        s=sqrt(p*(p-a)*(p-b)*(p-c)); 
        ss[i]=s;
        i++;
        cin>>x1>>y1>>x2>>y2>>x3>>y3;
    } 
    int n=i;
    for(int i=0; i<n; i++)
        printf("%.1f\n",ss[i]);
    return 0;
}

//已知三点坐标判断是逆时针输入还是顺时针输入
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int main()
{
    int x1,y1,x2,y2,x3,y3,i=0;
    double a,b,c,s,p;
    cin>>x1>>y1>>x2>>y2>>x3>>y3;
    while(x1 || y1 || x2 || y2 || x3 || y3)
    {
        cout<<((x3-x1)*(y2-y1)/(x2-x1)+y1>y3)<<endl;
        cin>>x1>>y1>>x2>>y2>>x3>>y3;
    } 
    return 0;
}